Translation of the abstract (English)

1. Introduction:
In transplantation medicine suppression of the immune system to prevent transplant rejection is inevitable. But in addition to the increased susceptibility to infections an increased risk of \\\\\\\\\\\\\\\"de novo\\\\\\\\\\\\\\\" and the recurrent tumor (up to 500-fold) is a serious problem. The immunosuppressant rapamycin is certified in more recent studies to have ...

Translation of the abstract (English)

1. Introduction: In transplantation medicine suppression of the immune system to prevent transplant rejection is inevitable. But in addition to the increased susceptibility to infections an increased risk of de novo and the recurrent tumor (up to 500-fold) is a serious problem. The immunosuppressant rapamycin is certified in more recent studies to have antiproliferative and antiangiogenic effects, which could solve this problem. So far, the effects of immunosuppressive drugs on the immune system and tumors were analyzed separately. In this study, to simulate the clinical situation of transplantation in combination with a tumor, rapamycin is compared to cyclosporine A in a combined tumor transplantation model in mice to the simultaneous effect of transplant rejection and tumor growth. 2. Materials and methods: The animals were randomly assigned 7 days after subcutaneous administration of syngeneic CT26 colon cancer cells, and treatment groups with different doses of cyclosporin A (40 mg/kg/d), rapamycin (1.5 and 4.5 mg/kg/d) and as a control group of NaCl 0.9% split. On day 7, we introduced an ear-heart transplant (C3H to Balb/c) and started the drug therapy. Then the animals were observed for a maximum of 4 weeks concerning graft survival and tumor growth.

3. Results: In the control group the tumor complications in all animals (7/7), approximately 17 days after transplantation, were the limiting factor in the beating heart, whereas here the tumor itself has had a certain immunosuppressive effect. Under rapamycin treatment the transplant stayed functionally intact up to the end of the experiment with reduced tumor growth (277 vs. 348 mm³ control, d 15) in all 6 mice. In contrast, the animals (7/7) under cyclosporine suffered after an average of 23 days (± 2.8) of the much higher tumor burden (545 vs. 348 mm³, d 15) with even vital transplants. 4. Conclusion: In this animal study, we were able to confirm that CsA does have a potent immunosuppressant, protective effect on transplanted organs, but an existing tumor is rather encouraged. In direct contrast, rapamycin in normal immunosuppressive doses protected transplanted organs and simultaneously can attack an existing tumor. Although the tumor with Rapa could not be eliminated, which was not expected, in addition with a conventional anti-neoplastic chemo-therapy it could mark an immense progress in transplantation medicine and reducing the dilemma in tumor treatment in transplant patients.